Diaphragm Check Valve

thingiverse

This is a low pressure free-floating diaphragm check valve, for gas or liquid. It will accept 3/8 inlet and outlet hose . A round diaphragm with a diameter of about 24mm from a material such as thin rubber will need to be provided. I used a 2 part silicone (30 shore) and made a thin sheet about 1.4mm thick and it worked great. The free-floating total distance is 2mm but you can make it bigger if you don't push-in the 2 valve pieces all the way together. I printed the two pieces upside down, (the big part on top), without support with 0.1mm layer height, 0.4mm nozzle, carbon fiber PETG, 20% infill and a 4mm brim (to keep them from falling during printing). There is a 0.1mm built-in clearance between the 2 parts but because holes tend to be printed smaller and differently depending on filament type/settings you might need to use your slicer settings to adjust the hole size. I printed the inlet part as-is and increased the size of the outlet to 100.8%. You can also sand the inlet to get the right size. This is what I did on my first try... I recommend using ironing for the contact surface of the inlet side to make it as flat and smooth as possible. This is the part in contact with the diaphragm. I sanded my first one with 300/600/1000 and 2000 grit sandpaper and It kept perfect vacuum. I didn't sand the second version and it worked good enough... You can glue the 2 parts together if you need to make the outlet side airtight. There is an arrow on the outlet to indicate flow direction.